Optical pickup device

ABSTRACT

Light from a light source is led to a condensing lens by a light leading unit and is condensed onto an optical recording medium by the condensing lens. Light reflected from the optical recording medium is led to a light sensing device through a spot adjustment lens facing the light sensing device. Between the spot adjustment lens and the light sensing device, a cylindrical dustproof member is provided. The full periphery of an optical path extending between the spot adjustment lens and the light sensing device is covered with the dustproof member. It can prevent intrusion of a foreign matter such as dusts into the optical path extending between the spot adjustment lens and the light sensing device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/686,089 filed on Oct. 14, 2003, which claims priority to Japaneseapplication No. 2002-300802 filed on Oct. 15, 2002 and No. 2002-375104filed on Dec. 25, 2002, whose priority is claimed under 35 USC §119, thedisclosure of all of which are incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical pickup device and, moreparticularly, to an optical pickup device capable of opticallyreproducing, recording, or erasing information to/from an opticalrecording medium such as a CD or DVD.

2. Description of the Background Art

Since a large amount of information can be recorded/reproduced at highdensity to/from an optical recording medium such as a CD or DVD, therange of uses including an audio-visual system and a computer is verywide. In particular, recently, it is requested to establish, practicallyuse, and spread techniques of recording information to a high-densityoptical recording medium. Among the techniques, the performance of anoptical pickup device used for recording/reproducing information to/froman optical recording medium is being increased. Therefore, it isrequested not only to enhance the performance of each of parts of theoptical pickup device but also to assure high positional precision ofeach of the parts so that light travels along a predetermined opticalaxis (design optical axis).

FIG. 14 is a perspective view showing an optical pickup device 1 ofPrior Art 1. FIG. 15 is a perspective view showing a part of a housing 7in which a light sensing device 5 and an opposed lens (hereinbelow,called a spot adjustment lens 6) in Prior Art 1 are provided. FIG. 16 isa cross section showing a part of the housing 7 in Prior Art 1. FIG. 17is a perspective view showing a part of the housing 7 before the lightsensing device 5 is provided in Prior Art 1. The optical pickup device 1of Prior Art 1 is constructed by including a light source 2, acondensing lens 3, a light leading part 4, and a light reception parthaving the light sensing device 5. Light (laser beam) emitted from thelight source 2 is condensed onto a not-shown optical recording medium(optical disk) by the condensing lens 3 and reflected by the opticalrecording medium. The light reflected from the optical recording mediumis made converged light by the spot adjustment lens 6 of the lightleading part 4 facing the light sensing device 5 and is led to the lightsensing device 5. The spot adjustment lens 6 and the light sensingdevice 5 are provided for the housing 7. An optical path 8 extendingbetween the spot adjustment lens 6 and the light sensing device 5 isopen without being surrounded by the housing 7. Also in the otherconventional optical pickup devices, although the light leading means ishoused in a casing, the optical path extending between a lens opposed toa light sensing device and the light sensing device is open withoutbeing surrounded, for example, because of a through hole for leadinglight to a condensing lens (refer to, for example, Japanese UnexaminedPatent Application Nos. 6-309813, 7-320293, and 11-149659).

FIG. 18 is a plan view showing an attachment state of a hologram laserunit in an optical pickup device of Prior Art 2 to a housing (refer to,for example, Japanese Unexamined Patent Application No. 2000-21013). Ahologram laser unit 71 is a semiconductor device in which a lightoutgoing part and a light receiving part are integrated. The opticalpickup device is held in a housing 70 in a state where the hologramlaser unit (hereinbelow, also called a laser unit) 71, a dichroic prism85, and a collimator lens 84 are disposed on the same optical axis. Thelaser unit 71 of the optical pickup device is attached to the housing 70as follows. First, the laser unit 71 is inserted into a laser holder 77and is pressed against the housing 70 by a laser press spring 75. Byinserting screws 79 to holes 78 formed at both the ends of the laserpress spring 75, each of the screws 79 is screwed into a screw hole 80formed in the housing 70. In an FPC (Flexible Pattern Circuit) 81 inwhich an operation circuit of the optical pickup device is formed, aplurality of holes are formed and a conduction land exists in theperiphery of each of the holes. A plurality of terminals 71 d at theends of the laser unit 71 are inserted into the holes of the FPC 81 andthe conduction lands and the terminals 71 d are soldered. Subsequently,the positions of the laser unit 71 and the laser holder 77 are adjustedso that information of an optical recording medium can be readaccurately. After that, the laser unit 71 and the laser holder 77 arefixed in adhesion positions 82, and the housing 70 and the laser holder77 are fixed in adhesion positions 83 by an adhesive. In FIG. 18,reference numeral 71 b denotes a diffraction device at the tip of thelaser unit 77. The arrow X indicates the lateral direction, the paintedcircle Y expresses the vertical direction, and the arrow Z expresses theoptical path direction.

In Prior Art 1, however, the optical path extending between the lightsensing device and the spot adjustment lens is in an open state. When aforeign matter such as dusts from the outside enters the optical path asan area where light is converged depending on use environments, lightcollides with the foreign matter and the travel of the light is deviatedfrom a predetermined optical axis (design optical axis). It causes aproblem that the performance of the optical pickup device deterioratesterribly.

In the case of the optical pickup device of Prior Art 2, it is requestedto improve the pickup precision by holding the interval between thecollimator lens 84 having the role of converting diffusion light emittedfrom the laser unit 71 into parallel light and the laser unit 71 at highprecision. However, the structure of the optical pickup device isinsufficient. Specifically, in the case of using the laser holder 77formed by using a member having strength as high as the housing 70, atthe time of assembling the optical pickup device, when the laser unit 71is attached into the laser holder and the position adjustment isperformed in the optical path direction (Z direction), the diffractiondevice 71 b at the tip of the laser unit 71 may come into contact with awall of the laser holder 77 by mistake and damage the diffractiondevice. Consequently, it is difficult to attach the laser unit 71 andperform the positional adjustment in the optical path direction.Therefore, it is difficult to make light emitted from the light sourceof the laser unit 71 toward the optical recording medium and lightreflected from the optical recording medium match with a predeterminedoptical axis (design optical axis) at high precision and to displayhigh-precision optical pickup performance.

As described above, the optical pickup devices of Prior Arts 1 and 2have a problem such that their high-precision optical pickup performancecannot be displayed due to their structures.

SUMMARY OF THE INVENTION

One of main objects of the invention is to provide an optical pickupdevice capable of displaying high-precision optical pickup performanceby making light emitted from a light outgoing part toward an opticalrecording medium and light reflected from the optical recording mediumtravel along a predetermined optical axis.

The invention provides an optical pickup device forrecording/reproducing information to/from an optical recording medium,comprising:

a light source for emitting light;

a condensing unit for condensing the light from the light source onto anoptical recording medium;

a light receiving unit having a light sensing device for receiving lightreflected by the optical recording medium;

a light leading unit having an opposed lens which faces the lightsensing device, for leading the light reflected by the optical recordingmedium to the light sensing device through the opposed lens; and

a cylindrical dustproof member for covering the full periphery of anoptical path extending between the opposed lens and the light sensingdevice.

According to the invention, light emitted from the light source iscondensed by the light condensing unit onto an optical recording medium.The light reflected by the optical recording medium is received by thelight sensing device of the light receiving unit. The light from theoptical recording medium is led from the opposed lens to the lightsensing device by the light leading unit. The optical path extendingbetween the opposed lens and the light sensing device is provided withthe cylindrical dustproof member. With the dustproof member, the fullperiphery of the optical path extending between the opposed lens and thelight sensing device is covered. Since the optical path extendingbetween the opposed lens and the light sensing device is covered withthe dustproof member, intrusion of a foreign matter such as dusts can beprevented. Thus, a problem such that light from the opposed lens isscattered by a foreign matter and led to an undesired light receptionposition of the light sensing device can be solved. Therefore, theperformance of the optical pickup device can be held excellently.

These and other objects of the present application will become morereadily apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing the configuration ofan optical pickup device as a first embodiment of the invention.

FIG. 2 is an exploded perspective view in which a dustproof member and ahousing are partially cut away.

FIG. 3 is a perspective view showing a part of the housing in a statewhere the light sensing means, the spot adjustment lens and thedustproof member are provided.

FIG. 4 is a cross section showing a part of the housing in a state wherethe light sensing means, the spot adjustment lens, and the dustproofmember are provided.

FIG. 5 is a cross section showing a part of the housing of an opticalpickup device in a second embodiment of the invention.

FIG. 6 is a cross section showing a part of the housing of an opticalpickup device of a third embodiment of the invention.

FIG. 7 is a cross section showing a part of the housing of an opticalpickup device in a fourth embodiment of the invention.

FIG. 8 is an enlarged cross section of a section S in FIG. 7.

FIG. 9 is a plan view of a main portion of an optical pickup device of afifth embodiment of the invention.

FIG. 10 is a perspective view of a main portion of the housing in thefifth embodiment.

FIG. 11 is a cross section taken along line A-A of FIG. 9.

FIG. 12 is a cross section taken along line B-B of FIG. 9.

FIG. 13 is a plan view of parts exploded from the optical pickup devicein the fifth embodiment.

FIG. 14 is a perspective view showing an optical pickup device of PriorArt 1.

FIG. 15 is a perspective view showing a part of a housing in which alight sensing device and an opposed lens in Prior Art 1 are provided.

FIG. 16 is a cross section showing a part of the housing in Prior Art 1.

FIG. 17 is a perspective view showing a part of the housing before thelight sensing device is provided in Prior Art 1.

FIG. 18 is a plan view showing an attachment state of a hologram laserunit in an optical pickup device of Prior Art 2 to a housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is also characterized in that the dustproof member is madeof an elastic material.

According to the invention, since the dustproof member is made of anelastic material, even in the case where an external force is applied tothe dustproof member, the external force can be absorbed. Therefore, theposition of the dustproof member can be prevented from being undesirablydeviated. A state in which the optical path extending between theopposed lens and the light sensing device is covered can be maintained.In the case of providing the dustproof member for a housing or the like,by providing the housing with a retaining part such as, a through holeand a pair of projection pieces, without using other holding memberssuch as an adhesive, the dustproof member can be easily retained by theretaining part and held by the housing. It can improve workability andprevent increase in the number of parts of the device.

The invention is also characterized in that the full periphery of a oneend portion in the axial direction of the dustproof member is in elasticcontact with the opposed lens, and the full periphery of the other endportion in the axial direction is in elastic contact with the lightsensing device.

According to the invention, the full periphery of a one end portion inthe axial direction of the dustproof member is in elastic contact withthe opposed lens, and the full periphery of the other end portion in theaxial direction is in elastic contact with the light sensing device.With the configuration, even in the case where the opposed lens and thelight sensing device are displaced to adjust their positions, the stateof contact of the dustproof member with the opposed lens and the lightsensing device can be maintained. Therefore, intrusion of a foreignmatter to the optical path extending between the opposed lens and thelight sensing device can be prevented with reliability.

The invention is also characterized in that the dustproof member expandstoward both the ends in the axial direction.

According to the invention, since the dustproof member expands towardboth the ends in the axial direction, as compared with a dustproofmember whose both the ends in the axial direction are not deformed inthe axial direction, the dustproof member can be deformed in the axialdirection more easily. Consequently, even in the case where an externalforce in the axial direction is applied to the dustproof member, thedustproof member is easily deformed in the axial direction, so that thedustproof member can be prevented from exerting an adverse influence onthe optical path.

The invention is also characterized in that the dustproof member isformed in a bellows shape.

According to the invention, since the dustproof member is formed in abellows shape, as compared with a dustproof member of which both theends in the axial direction are not deformed in the axial direction, thedustproof member can be deformed in the axial direction more easily.Even in the case where an external force in the axial direction isapplied to the dustproof member, the dustproof member is easily deformedin the axial direction, so that the dustproof member can be preventedfrom exerting an adverse influence on the optical path.

The invention is also characterized by further including a housing forholding the light sensing device so as to be rotatable around thereference axis line which is parallel to the optical axis of the opposedlens and so as to be displaceable in the direction perpendicular to thereference axis line, holding the opposed lens so as to be displaceablealong the optical axis, and holding the dustproof member so that boththe ends in the axial direction are displaceable in the axial directionby the intermediate portion in the axial direction.

According to the invention, the light sensing device is held by thehousing so as to be rotatable around the reference axis line which isparallel to the optical axis of the opposed lens and so as to bedisplaceable in the direction perpendicular to the reference axis line.The opposed lens is held by the housing so as to be displaceable alongthe optical axis. The dustproof member is held by the housing so thatboth the ends in the axial direction are displaceable in the axialdirection by the intermediate portion in the axial direction. With theconfiguration, even in the case where the light sensing device and theopposed lens are displaced with respect to the housing as describedabove, the dustproof member is not easily influenced by thedisplacement. In other words, even in the case where the light sensingdevice and the opposed lens are displaced with respect to the housing asdescribed above, the axial layout state of the dustproof member can bemaintained. It can prevent a change in the axial layout state of thedustproof member and exertion of an adverse influence on the opticalpath. Therefore, the dustproof effect can be held with reliability.

The invention is also characterized in that at least the surface of acontact portion which is in contact with the light sensing device, ofthe dustproof member is formed as a curved surface.

According to the invention, at least the surface of a contact portionwhich is in contact with the light sensing device, of the dustproofmember is formed as a curved surface. As compared with the case wherethe surface of the contact portion which is in contact with the lightsensing device is a plane, the contact area between the dustproof memberand the light sensing device can be made smaller. Therefore, aninfluence exerted by displacement of the light sensing device can bereduced so as not to be easily exerted. For example, in the case ofdisplacing the light sensing device along a virtual plane perpendicularto the optical axis of the opposed lens, as compared with the case ofdisplacing the light sensing device along the optical axis, thedustproof member exerts an influence on the optical path due to adisplacement of the light sensing device more easily. By forming thesurface of the contact portion which is in contact with the lightsensing device, of the dustproof member as a curved surface, aninfluence exerted on the optical path due to displacement of the lightsensing device can be reduced with reliability. The dustproof member canbe also prevented from damaging the light sensing device.

The invention is also characterized in that at least the innerperipheral face of the dustproof member is black.

According to the invention, at least the inner peripheral face of thedustproof member is black, so that light can be prevented from beingirregularly reflected by the inner peripheral face of the dustproofmember. Consequently, stray light generated by irregular reflection canbe reliably prevented from being received by the light sensing device.

The invention also provides an optical pickup device comprising: ahousing; an optical part which is attached to the housing and includes alight source for emitting a laser beam and/or a light sensing devicecapable of detecting the laser beam; and an attaching means which isprovided in an optical part attaching position in the housing and canattach the optical part directly to the housing, wherein the attachingmeans has an elastic buffer for protecting the light source and/or thelight sensing device of the optical part at the time of attaching theoptical part to the housing and adjusting the position of the opticalpart in an optical path length direction.

Examples of an information recording medium as an object of the opticalpickup device of the invention are optical disks such as LD, CD, CD−ROM,DVD−ROM, CD−R, DVD−R, CD−RW, DVD−RW, DVD+R, DVD+RW, and DVD−RAM andmagneto-optic disks such as MO and MD. Particularly, the optical pickupdevice of the invention can be suitably used for writable DVD−R, DVD−RW,DVD+R, DVD+RW, DVD−RAM, and the like requiring high precision inattachment of an optical part.

In the invention, examples of the optical part to be attached to thehousing and having the light source for emitting a laser beam and/or thelight sensing device capable of detecting the laser beam are a hologramlaser unit, a semiconductor laser, and a light sensing device.Particularly, a hologram laser unit requiring the highest precision inadjustment of distance to a collimator lens (position adjustment in theoptical path direction) is suitable.

Hereinbelow, when simply called an optical part, it refers to an opticalpart having a light source for emitting a laser beam and/or a lightsensing device capable of detecting the laser beam, such as a hologramlaser unit, a semiconductor laser, and a light sensing device.

According to the invention, at the time of attaching an optical partsuch as a hologram laser unit, a semiconductor laser, a light sensingdevice, or the like to a housing, by providing the elastic buffer in theattachment position, the light source and/or the light sensing device ofthe optical part are/is protected by the elastic buffer. The lightsource and/or the light sensing device can be prevented from coming intocontact with the wall of the housing made of metal or plastic having acertain degree of strength and from being damaged. As described above,since the optical part is protected by the elastic buffer, the breakageratio largely decreases, the laser holder which is conventionallynecessary becomes unnecessary, a manufacturing process and the number ofparts of a laser holder which is not easily processed can be reduced,and attachment of the laser holder to the housing and the positionaladjustment which are conventionally performed are not performed. Thus,the manufacturing cost is largely reduced and the assembly workabilityimproves.

The adjustment space in the optical path length direction is assured bythe elastic buffer, so that the optical part can be (slightly) moved inthe optical path length direction by elastic deformation of the elasticbuffer at the time of adjusting the position of the optical part in theoptical path length direction, and the positional adjustment can beperformed easily at high precision. Therefore, the precision of a laserbeam (diffusion light) emitted to the collimator lens and/or precisionof a laser beam (focused beam) from the collimator lens is improved, andinformation can be recorded/reproduced to/from a high-density opticaldevice medium more reliably.

In the invention, as the material of the elastic buffer, a sponge madeof a natural sea sponge, a synthetic resin or a rubber is used. In theelastic buffer, a laser beam passing window for passing a laser beam isformed in a position facing the light source and/or the light sensingdevice of the optical part. By forming the elastic buffer in a shapecovering the light sourse and/or the light sensing device of the opticalpart, the dustproof function and the light shielding function can beadded. To increase the light shielding performance, the color of theelastic buffer is preferably black.

In the invention, when the housing has a recessed portion for insertingand attaching the optical part in the horizontal optical path directionand has a structure that the elastic buffer is disposed along the wallface in the deep portion of the recessed portion, the recessed portionserves as a storage space capable of housing the whole optical part soas to protect it. At the time of inserting the optical part into therecessed portion, the elastic buffer can protect the optical part sothat the light source and/or the light sensing device does/do not comeinto contact with the wall face in the deep portion.

As a component of the attaching means, a projection to which an adhesivefor fixing the elastic buffer is to be applied may be provided for therecessed portion. With the configuration, the elastic buffer can beeasily attached at a proper level.

In the invention, the recessed portion of the attaching means have atemporary holding portion so that the optical part is temporarily heldin a state where movement in the vertical direction is regulated. In theinvention, the temporary holding portion may have a structure formed onan inner face of the recessed portion and sandwiching the optical partinserted in the recessed portion from top and bottom, for example, astructure constructed by a pair of upper and lower projection pieceswhich project to the inside from a left inner face and a pair of upperand lower projection pieces which project to the inside from a rightinner face toward an opening of the recessed portion which is open inthe horizontal direction. In such a manner, the temporary holdingportion may have a simple structure. By the temporary holding portion,the optical part inserted in the recessed portion is temporarily held ata level corresponding to the design optical axis and is in parallel. Inthe invention, “temporary holding” is defined as holding of the opticalpart so as to be movable in at least the optical path length direction.In the case where the width (in the horizontal direction) of therecessed portion is set to be larger than the width of the optical part,the optical part is temporarily held by the temporary holding portion soas to be movable in the optical path length direction and the horizontaldirection, so that position adjustment in two directions is performed.Further, the temporary holding portion can also serve as a portion towhich an adhesive for fixing the optical part sandwiched from top andbottom is applied, so that it is convenient.

Embodiments of the invention will be described hereinbelow withreference to the drawings. The invention, however, is not limited to theembodiments.

First Embodiment

FIG. 1 is a perspective view schematically showing the configuration ofan optical pickup device 10 as a first embodiment of the invention. InFIG. 1, for easier understanding, an optical path is shown in asimplified manner. An optical pickup device 10 is a device forrecording/reproducing information to/from an optical recording medium11. The optical recording medium 11 is an optical disk such as a compactdisc (abbreviated as CD), a digital versatile disc (abbreviated as DVD),or the like. The optical pickup device 10 is constructed by including alight source 12, a condensing lens 13, a light leading means 14, and alight sensing device 15.

The light source 12 is means for emitting light and is realized by, forexample, a semiconductor laser. The condensing lens 13 as lightcondensing means condenses light from the light source 12 onto aninformation recording face 16 of the optical recording medium 11. Thecondensing lens 13 is held by a lens holder 17. The lens holder 17 isheld by a not-shown holder so as to be displaced in a focusing directionF and a tracking direction T. The focusing direction F is a directiontoward/apart from the information recording face 16 of the opticalrecording medium 11. The tracking direction T is a direction of scanninga recording area in the information recording face 16 of the opticalrecording medium 11. The lens holder 17 is displaced in the focusingdirection F and the tracking direction T by a magnetic action of drivingmeans (not shown) realized by, for example, a coil and a permanentmagnet piece. The condensing lens 13 is displaced in the focusingdirection F and the tracking direction T and light from the condensinglens 13 forms a small spot on the information recording face 16.

The light leading means 14 leads light emitted from the light source 12to the optical recording medium 11 and leads light reflected from theoptical recording medium 11 to the light sensing unit 15 which will bedescribed later. The light leading means 14 is constructed by includinga grating lens 20, a beam splitter 21, a collimator lens 22, areflection mirror 23, and a spot adjustment lens 24. The grating lens 20has a diffraction grating and divides incident light into a plurality ofrays. When a light beam which is linear polarized in an arbitrarydirection enters, the beam splitter 21 splits the linear polarized lightbeam into a P-direction component and an S-direction component,transmits the P-direction component, and reflects the S-directioncomponent at 90 degrees. The beam splitter 21 is formed in a flat plateshape or a rectangular parallelepiped shape. In the example of FIG. 1,the beam splitter 21 has a flat plate shape. The collimator lens 22converts incident light into parallel light. The reflection mirror 23reflects the led light to change the travel direction of the light. Thespot adjustment lens 24 as an opposed lens is a lens for condensing thelight and faces a light sensing device 30 which will be described later.The spot adjustment lens 24 has, for example, a cylindrical body 24 aand a lens 24 b for condensing light and has a configuration that thecylindrical body 24 a and the lens 24 b are integrally displaced alongan optical axis L24 of the lens 24 b.

The light source 12, grating lens 20, and beam splitter 21 are disposedin this order at intervals in a direction perpendicular to a virtualplane in which a plurality of gratings are arranged in the grating lens20. In the example of FIG. 1, the direction perpendicular to the virtualplane is parallel to the tracking direction T. The spot adjustment lens24, beam splitter 21, collimator lens 22, and reflection mirror 23 aredisposed in this order at intervals in the focusing direction F and theabove-described direction. The collimator lens 22 is disposed on thesame side as the grating lens 20 with respect to the beam splitter 21.The condensing lens 13 and the reflection mirror 23 are disposed with aspace in the focusing direction F. Further, the condensing lens 13 isdisposed between the optical recording medium 11 and the reflectionmirror 23.

When light is emitted from the light source 12 as shown by an arrow 26 ain FIG. 1, the light from the light source 12 enters the grating lens20. The light entered and passed through the grating lens 20 is splitinto a plurality of light beams, which are led as shown by an arrow 26 bin FIG. 1 and are incident on the beam splitter 21. The beam splitter 21reflects the light from the grating lens 20 only by 90 degrees. Thelight reflected by the beam splitter 21 is led as shown by an arrow 26 cof FIG. 1 and is incident on the collimator lens 22. The light incidenton the collimator lens 22 is converted by the collimator lens 22 toparallel light. The parallel light is led to the reflection mirror 23 asshown by an arrow 26 d of FIG. 1. The light from the collimator lens 22is reflected by the reflection mirror 23 so as to become parallel to thefocusing direction F. The light reflected by the reflection mirror 23 isled as shown by an arrow 27 a of FIG. 1 and is incident on thecondensing lens 13. The light incident on the condensing lens 13 is ledas shown by an arrow 27 b of FIG. 1 and is condensed onto theinformation recording face 16 of the optical recording medium 11. Thelight reflected from the optical recording medium 11 is led as shown byan arrow 27 c of FIG. 1 and is incident on the condensing lens 13. Thelight incident on the condensing lens 13 from the optical recordingmedium 11 is led as shown by an arrow 27 d of FIG. 1 and is led to thereflection mirror 23. The light from the condensing lens 13 is reflectedby the reflection mirror 23, led as shown by an arrow 28 a of FIG. 1,and enters the collimator lens 22. The light entered the collimator lens22 from the reflection mirror 23 is led as shown by an arrow 28 b ofFIG. 1 and is incident on the beam splitter 21. The light incident onthe beam splitter 21 passes through the beam splitter 21, is led asshown by an arrow 28 c of FIG. 1 and enters the spot adjustment lens 24.The light incident on the spot adjustment lens 24 is converted by thespot adjustment lens 24 to converged light which is led as shown by anarrow 28 d of FIG. 1 and received by the light sensing means 15 whichwill be described below.

The light sensing means 15 has the light sensing device 30 and receivesthe light reflected from the optical recording medium 11 by the lightsensing device 30. The light sensing means 15 has a base portion 31having a flat plate shape and the light sensing device 30 is provided onthe base portion 31. The light sensing device 30 is realized by, forexample, a photo diode. The light sensing device 30 receives light ledfrom the spot adjustment lens 24 by a light receiving portion 30 a(refer to FIG. 4). The light sensing device 30 converts the light intoan electric signal on the basis of the amount of the received light. Theelectric signal includes an information signal regarding the informationrecording face 16 and a servo signal for controlling a displacement inthe focusing direction F and the tracking direction T. On the basis ofthe information signal and the servo signal, driving means and the likeare controlled by not-shown control means so that the light is condensedto a desired position in the information recording face 16. In such amanner, the optical pickup device 10 records/reproduces informationto/from the optical recording medium 11.

FIG. 2 is an exploded perspective view in which a dustproof member 35and a housing 40 are partially cut away. FIG. 3 is a perspective viewshowing a part of the housing 40 in a state where the light sensingmeans 15, the spot adjustment lens 24 and the dustproof member 35 areprovided. FIG. 4 is a cross section showing a part of the housing 40 ina state where the light sensing means 15, the spot adjustment lens 24,and the dustproof member 35 are provided. In FIGS. 2 to 4, for easierunderstanding, the optical path is shown in a simplified manner. Betweenthe spot adjustment lens 24 and the light sensing device 30, thedustproof member 35 having a cylindrical shape is disposed. Thedustproof member 35 is a member for covering the full periphery of anoptical path 29 extending between the spot adjustment lens 24 and thelight sensing device 30 (“the optical path 29 extending between the spotadjustment lens 24 and the light sensing device 30” will be also simplycalled “optical path 29”). The dustproof member 35 is made of an elasticmaterial. Examples of the elastic material are a rubber elastic membercalled elastomer and silicone rubber. The dustproof member 35 is formedso as to expand toward both the ends 36 in the axial direction.Concretely, the dustproof member 35 has an outer shape of, roughly, aright circular cylinder and is formed so that its inner peripheral face37 expands toward both the ends 36 in the axial direction. At least theinner peripheral face 37 of the dustproof member 35 is black. In theembodiment, the whole dustproof member 35 is black.

The optical pickup device 10 further includes the housing 40. Thehousing 40 holds the light source 12, light leading unit 14, lightsensing device 30, and dustproof member 35. The examples of FIGS. 3 and4 show a state where the spot adjustment lens 24, the light sensingdevice 30, and the dustproof member 35 are held by the housing 40. Thespot adjustment lens 24 and the light sensing device 30 are disposed inpositions so as to face each other and provided for the housing 40. Inthe housing 40, to enhance the strength, a plate-shaped partition wall41 of which thickness direction is perpendicular to the optical axis L24of the spot adjustment lens 24 is provided between the spot adjustmentlens 24 and the light sensing device 30.

In one of side ends 42 in the longitudinal direction of the partitionwall 41, a first side portion 43 extending in one direction in thethickness direction is provided. In the other side end 44 in thelongitudinal direction of the partition wall 41, a second side portion45 extending in one direction of the thickness direction is provided.The first side portion 43 has a first surface 46 facing the second sideportion 45 and perpendicular to the longitudinal direction of thepartition wall 41. The second side portion 45 has a second surface 47facing the first side portion 43 and perpendicular to the longitudinaldirection of the partition wall 41. The interval between the firstsurface 46 and the second surface 47 is almost the same as the outsidediameter of the spot adjustment lens 24. The spot adjustment lens 24 isdisposed in an area sandwiched by the first side portion 43 and thesecond side portion 45. A part of the area of the outer peripheral face48 of the spot adjustment lens 24 is in contact with the first surface46 of the first side portion 43 and another part of the area of theouter peripheral face 48 is in contact with the second surface 47 of thesecond side portion 45. The spot adjustment lens 24 is held in thehousing 40 so as to be displaceable in a first lens adjustment directionA1 and a second lens adjustment direction A2. The first lens adjustmentdirection A1 is a direction along the optical axis L24 of the spotadjustment lens 24 and is a direction in which the spot adjustment lens24 approaches the light sensing device 30. The second lens adjustmentdirection A2 is a direction along the optical axis L24 of the spotadjustment lens 24 and is a direction in which the spot adjustment lens24 moves apart from the light sensing device 30. The spot adjustmentlens 24 is displaced in the first and second lens adjustment directionsA1 and A2 by, for example, a means for displacing the spot adjustmentlens 24 so that light is condensed to a small spot to form an image onthe light sensing device 30. In the embodiment, the thickness directionof the partition wall 41 is parallel to the optical axis L24 of the spotadjustment lens 24 held by the housing 40.

The first side portion 43 has a first projected portion 49 whichprojects in the other direction of the thickness direction of thepartition wall 41 (first lens adjustment direction A1). The second sideportion 45 has a second projected portion 50 which projects in the otherdirection of the thickness direction of the partition wall 41 (secondlens adjustment direction A1). The first and second projected portions49 and 50 project to a degree that, at the time of providing the lightsensing device 30 for the housing 40, the dustproof member 35 can bepressed by the light sensing device 30 so as to be deformed. The firstprojected portion 49 has a surface 49 a serving as a plane perpendicularto the thickness direction of the partition wall 41, and the secondprojected portion 50 has a surface 50 a serving as a plane perpendicularto the thickness direction of the partition wall 41. The surface 49 a ofthe first projected portion 49 and the surface 50 a of the secondprojected portion 50 are included in a virtual plane perpendicular tothe thickness direction of the partition wall 41.

The base portion 31 of the light sensing means 15 is in contact with thesurface 49 a of the first projected portion 49 and the surface 50 a ofthe second projected portion 50 in the light sensing device 30. Thelight sensing device 30 is held by the housing 40 so as to bedisplaceable along the virtual plane including the surface 49 a of thefirst projected portion 49 and the surface 50 a of the second projectedportion 50. Concretely, the light sensing device 30 is held by thehousing 40 so as to be rotatable around a reference axis line L15 anddisplaceably in a first adjustment direction B1 and a second adjustmentdirection B2 as directions perpendicular to the reference axial lineL15. The first and second adjustment directions B1 and B2 areperpendicular to each other. The reference axis line L15 is, concretely,an axis parallel to the optical axis L24 of the spot adjustment lens 24held in the housing 40. The first adjustment direction B1 is, forexample, a direction parallel to the focusing direction F and the secondadjustment direction B2 is, for example, a direction parallel to thetracking direction T. As described above, the light sensing device 30 isdisplaced in a range where its light receiving portion 30 a can receivelight from the spot adjustment lens 24 and receives light from the spotadjustment lens 24. The light sensing device 30 is displaced by, forexample, means for displacing the light sensing device 30.

In the partition wall 41, a through hole 51 is opened so as to penetratethe partition wall 41 in the thickness direction. The inner peripheralface 52 facing the through hole 51 of the partition wall 41 is smalleras compared with the outside diameter of the dustproof member 35 and hasa diameter of a degree that light from the spot adjustment lens 24 canbe led to the light sensing device 30 in a state where the dustproofmember 35 is inserted in the through hole 51. The dustproof member 35 isinserted in the through hole 51 and is provided for the partition wall41. In an intermediate portion 38 in the axial direction of thedustproof member 35, a recessed portion 39 which is a partial arearecessed toward the inner radius in the whole circumferential directionis provided. The recessed portion 39 is provided in the intermediateportion 38 in the axial direction of the dustproof member 35 near to theother end portion 58. The other end portion 58 of the dustproof member35 is an end on the other side (the light sensing device 30 side) in theaxial direction in both the ends 36 in the axial direction of thedustproof member 35. At the time of providing the dustproof member 35for the partition wall 41, an inner peripheral portion 53 having aninner peripheral face 52 of the partition wall 41 is fit in the recessedportion 39 of the intermediate portion 38 in the axial direction. In astate where the dustproof member 35 is provided for the partition wall41, the dustproof member 35 is disposed so that its axial direction isparallel to the thickness direction of the partition wall 41. At thetime of inserting the dustproof member 35 in the through hole 51, sincethe dustproof member 35 is made of an elastic material, even in the casewhere the outside diameter of the dustproof member 35 is larger than thediameter of the through hole 51, the dustproof member 35 can be deformedand easily inserted in the through hole 51.

Further, after the dustproof member 35 is provided for the housing 40,the inner peripheral portion 53 of the partition wall 41 is fit in therecessed portion 39 of the intermediate portion 38 in the axialdirection of the dustproof member 35 and is disposed near to the otherend 58 with respect to the dustproof member 35. In a state where thedustproof member 35 is provided for the partition wall 41, theintermediate portion 38 in the axial direction of the dustproof member35 comes into elastic contact with the inner peripheral portion 53 ofthe partition wall 41. By providing the dustproof member 35 for thepartition wall 41, even in the case where the spot adjustment lens 24 isdisplaced in the first lens adjustment direction A1, the spot adjustmentlens 24 is prevented from being disengaged from the partition wall 41and only one end portion 55 of the dustproof member 35 is deformed. Insuch a manner, the dustproof member 35 is held by the housing 40 so thatboth the ends 36 in the axial direction are displaceable in the axialdirection in the intermediate portion 38 in the axial direction. At thetime of providing the dustproof member 35 for the housing 40, it isunnecessary to use other holding members such as an adhesive, the numberof parts of the device can be prevented from increasing.

The spot adjustment lens 24 is provided for the housing 40 so as to facethe one end portion 55 of the dustproof member 35. In a state where thespot adjustment lens 24 and the dustproof member 35 are provided for thehousing 40, an axis L35 of the dustproof member 35 is coaxial with theoptical axis L24 of the spot adjustment lens 24. The one end portion 55of the dustproof member 35 is the end portion on one side (spotadjustment lens 24 side) out of both the end portions 36 in the axialdirection of the dustproof member 35. The spot adjustment lens 24 isheld by the housing 40 in a state where the one end portion 55 of thedustproof member 35 is pressed and deformed in the first lens adjustmentdirection A1. In the one end portion 55 of the dustproof member 35, thefull periphery of a lens contact portion 56 is in elastic contact withthe spot adjustment lens 24. Concretely, the lens contact portion 56 isin elastic contact with the full periphery of a one end portion 57 inthe axial direction facing the dustproof member 35 of the cylindricalbody 24 a of the spot adjustment lens 24. The inside diameter of thelens contact portion 56 is larger than that of the one end portion 57 inthe axial direction of the cylindrical body 24 a of the spot adjustmentlens 24.

When the spot adjustment lens 24 is displaced in the first lensadjustment direction A1, the lens contact portion 56 of the dustproofmember 35 is pressed and deformed in the axial direction. When the spotadjustment lens 24 is displaced in the second lens adjustment directionA2, the lens contact portion 56 of the dustproof member 35 is deformedin the axial direction so as to be reset to a natural state again inwhich an external force is not applied. Since the dustproof member 35 ismade of an elastic material, the lens contact portion 56 is deformed asthe spot adjustment lens 24 is displaced. Further, since the innerperipheral face 37 of the dustproof member 35 expands towards both theends 36 in the axial direction, the dustproof member 35 is not deformedin the axial direction. However, the one end portion 55 of the dustproofmember 35 is deformed more easily as compared with a dustproof memberhaving, for example, a right cylindrical shape. Since the one endportion 55 of the dustproof member 35 is deformed as the spot adjustmentlens 24 is displaced, the state of contact between the dustproof member35 and the spot adjustment lens 24 is maintained.

The light sensing device 30 is disposed so as to face the other endportion 58 of the dustproof member 35. The light sensing device 30 isheld by the housing 40 in a state where it presses against the other endportion 58 of the dustproof member 35 in the axial direction and theother end portion 58 is deformed. At the time of pressing the lightsensing device 30 against the dustproof member 35, since the dustproofmember 35 expands towards both the ends 36 in the axial direction, forexample, as compared with a dustproof member having a right circularcylinder shape, the other end portion 58 of the dustproof member 35 canbe deformed in the axial direction more easily. Further, since the otherend portion 58 of the dustproof member 35 expands toward the other endportion 58, even in the case where the light sensing device 30 ispressed against the other end portion 58 of the dustproof member 35 andthe other end portion 58 is deformed, the optical path 29 can beprevented from being interrupted due to deformation of the innerperipheral face of the other end portion 58. In the other end portion 58of the dustproof member 35, the full periphery of a device contactportion 59 which is in elastic contact with the light sensing device 30is in elastic contact with the light sensing device 30.

When the light sensing device 30 is allowed to rotate around thereference axis line L15 or is displaced in the first adjustmentdirection B1 and the second adjustment direction B2, the contact areawith the light sensing device 30 of the dustproof member 35 becomessmaller as compared with, for example, that of a dustproof member havinga right circular cylinder shape. As compared with a dustproof memberhaving a right circular cylinder shape, the other end portion 58 of thedustproof member 35 does not easily rotate around the reference axisline L15 and is not easily deformed in the first and second adjustmentdirections B1 and B2. Therefore, the state of contact between thedustproof member 35 and the light sensing device 30 is maintained,thereby enabling an adverse influence exerted by intrusion of a foreignmatter such as dusts to the optical path 29 to be prevented. Asdescribed above, light from the spot adjustment lens 24 passes throughthe area surrounded by the dustproof member 35 and is received by thelight sensing device 30 with reliability.

To assure the performance of the optical pickup device 10, it is a bigissue how to prevent intrusion of a foreign matter such as dusts into anoptical path initially or in accordance with environments in which thedevice is used. Initially, the quality can be assured by improving themanufacture environment of the optical pickup device 10. However,depending on the state of environments in which the device is used, aforeign matter may intrude in an optical path. It may cause a problemsuch that information cannot be excellently recorded/reproduced to/fromthe optical recording medium 11, and the performance of the opticalpickup device 10 deteriorates sharply. Particularly, the optical path 29extending between the spot adjustment lens 24 and the light sensingdevice 30 is an area where light is converged, so that the optical path29 is easily influenced by being interrupted by a foreign matter such asdusts. Since the optical path 29 is reliably protected from the outsideby being covered with the dustproof member 35 as described above, theoptical path 29 can be kept in a hermetic state under any environment.

According to the embodiment, light emitted from the light source 12 iscondensed onto the optical recording medium 11 by the condensing lens13. The light reflected from the optical recording medium 11 is receivedby the light sensing device 30 of the light sensing means 15. The lightfrom the optical recording medium 11 is led from the spot adjustmentlens 24 to the light sensing device 30 by the light leading unit 14. Theoptical path 29 extending between the spot adjustment lens 24 and thelight sensing device 30 is provided with the cylindrical-shapeddustproof member 35. By the dustproof member 35, the full periphery ofthe optical path 29 extending between the spot adjustment lens 24 andthe light sensing device 30 is covered. Since the optical path 29 iscovered with the dustproof member 35, intrusion of a foreign matter suchas dusts can be prevented. It can solve the problem such that light fromthe spot adjustment lens 24 is scattered by a foreign matter and led toan undesired light reception position of the light sensing device 30.Therefore, the performance of the optical pickup device 10 can be heldpreferably.

Further, according to the embodiment, the dustproof member 35 is made ofan elastic material. Consequently, even if an external force is appliedto the dustproof member 35, the external force can be absorbed and theposition in which the dustproof member 35 is disposed can be preventedfrom being undesirably deviated. Thus, the state in which the opticalpath 29 is covered can be maintained. Further, in the case of providingthe dustproof member 35 for the housing 40 or the like, by providing thethrough hole 51 and a retaining member such as a pair of projectionpieces for the housing 40 for example, without using another holdingmember such as an adhesive, the dustproof member 35 can be easilyprovided for the retaining member and held by the housing 40.Consequently, the workability can be improved and the number of parts ofthe device can be prevented from increasing.

Further, according to the embodiment, the full periphery of the one endportion 55 of the dustproof member 35 is elastically in contact with thespot adjustment lens 24, and the full periphery of the other end portion58 of the dustproof member 35 is elastically in contact with the lightsensing device 30. Consequently, even in the case where the position isadjusted by displacing the spot adjustment lens 24 and the light sensingdevice 30, the state of contact with the spot adjustment lens 24 and thelight sensing device 30, of the dustproof member 35 can be maintained.Therefore, intrusion of a foreign matter to the optical path 29extending between the spot adjustment lens 24 and the light sensingdevice 30 can be prevented with reliability.

Further, according to the embodiment, the dustproof member 35 expandstowards both the ends 36 in the axial direction, so that the dustproofmember 35 can be deformed in the axial direction more easily as comparedwith a dustproof member whose both the ends 36 in the axial directionare not deformed in the axial direction. With the configuration, forexample, even in the case where the spot adjustment lens 24 and thelight sensing device 30 are displaced in the axial direction, both theends 36 in the axial direction of the dustproof member 35 are deformedin the axial direction, so that occurrence of a problem such that thedustproof member 35 interrupts the optical path can be prevented.

Further, according to the embodiment, the light sensing device 30 isheld by the housing 40 so as to be rotatable around the reference axisline L15 parallel to the optical axis L24 of the spot adjustment lens 24and displaceable in the first adjustment direction B1 and the secondadjustment direction B2 perpendicular to the reference axis line L15.The spot adjustment lens 24 is held by the housing 40 so as to bedisplaceable along the optical axis L24. The dustproof member 35 is heldby the housing 40 so that both the ends 36 in the axial direction aredisplaceable in the axial direction in the intermediate portion 38 inthe axial direction. With the configuration, even in the case where thelight sensing device 30 and the spot adjustment lens 24 are displacedwith respect to the housing 40, the dustproof member 35 is not easilyinfluenced by the displacement. In other words, even in the case wherethe light sensing device 30 and the spot adjustment lens 24 aredisplaced with respect to the housing 40, the axial layout state of thedustproof member 35 can be maintained. It prevents a change in the axiallayout state of the dustproof member 35 and exertion of an adverseinfluence on the optical path. Therefore, the dustproof effect can beheld with reliability.

Further, according to the embodiment, at least the inner peripheral face37 of the dustproof member 35 is black, so that light can be preventedfrom being irregularly reflected by the inner peripheral face 37 of thedustproof member 35. Consequently, stray light generated by irregularreflection can be reliably prevented from being received by the lightsensing device 30.

Second Embodiment

FIG. 5 is a cross section showing a part of the housing 40 of an opticalpickup device 10 a in a second embodiment of the invention. The opticalpickup device 10 a of the embodiment is similar to the optical pickupdevice 10 of the first embodiment shown in FIGS. 1 to 4, so that onlythe different points will be described. In the optical pickup device 10a of the second embodiment, components similar to those of the opticalpickup device 10 of the first embodiment are designated by the samereference numerals. In the optical pickup device 10 a of the secondembodiment, in place of the dustproof member 35 of the optical pickupdevice 10 of the first embodiment, a dustproof member 35 a of whichinner peripheral face 37 and outer peripheral face 60 expand toward boththe ends 36 a in the axial direction is provided. In the example of FIG.5, both the ends 36 a in the axial direction of the dustproof member 35a are formed in a cone shape in which the inner peripheral face 37 andthe outer peripheral face 60 expand toward both the ends 36 a in theaxial direction.

A lens contact portion 56 a of a one end portion 55 a of the dustproofmember 35 a is in elastic contact with the spot adjustment lens 24. Whenthe spot adjustment lens 24 is displaced in the first lens adjustmentdirection A1, the one end portion 55 a of the dustproof member 35 a isdeformed in the axial direction so as to further expand. When the spotadjustment lens 24 is displaced in the second lens adjustment directionA2, the one end portion 55 a of the dustproof member 35 a is deformed inthe axial direction so as to be reset to a natural state where noexternal force is applied. By forming the one end portion 55 a of thedustproof member 35 a in a cone shape in which the inner peripheral face37 and the outer peripheral face 60 expand toward the one end portion 55a, for example, as compared with a dustproof member having a rightcylindrical shape, the one end portion 55 a in the axial direction canbe deformed in the axial direction more easily.

A device contact portion 59 a of the other end portion 58 a of thedustproof member 35 a is in elastic contact with the light sensingdevice 30. Since the inner peripheral face 37 and the outer peripheralface 60 of the other end portion 58 a of the dustproof member 35 aexpand toward the other end portion 58 a, the other end portion 58 a canbe deformed in the axial direction more easily as compared with adustproof member having, for example, a right circular cylinder shape.For example, in the case where the light sensing device 30 is providedin the housing 40 in a state where it is pressed against the dustproofmember 35 a, the other end portion 58 a of the dustproof member 35 a isdeformed so as to further expand and can be elastically in contact withthe light sensing device 30.

Further, in the intermediate portion 38 a in the axial direction of thedustproof member 35 a, an annular projection piece 61 which projectstoward the outside in the radial direction is provided in the wholeperiphery of the cylindrical portion of the right circular cylindricalshape. The projection piece 61 is provided near to the one end portion55 a in the intermediate portion 38 a in the axial direction of thedustproof member 35 a. In a state where the dustproof member 35 a isprovided for the partition wall 41, the full periphery of the projectionpiece 61 is in elastic contact with the surface 41 a facing thedustproof member 35 a of the partition wall 41. The projection piece 61prevents deviation of the dustproof member 35 a with respect to thehousing 40 and deformation of the inner peripheral face in theintermediate portion 38 a in the axial direction due to displacement ofthe spot adjustment lens 24 and the light sensing device 30.

Further, the portion between the projection piece 61 of the dustproofmember 35 a and the one end portion 55 a has a shape which is recessedin the radial direction as compared with the dustproof member 35 in thefirst embodiment. In other words, the portion sandwiched between thespot adjustment lens 24 of the dustproof member 35 a and the partitionwall 41 is formed thinner as compared with that of the dustproof member35 in the first embodiment. With the configuration, in a state whereonly the one end portion 55 a of the dustproof member 35 a is moreeasily deformed in the axial direction, the dustproof member 35 a isheld on the partition wall 41 by the projection piece 61 without beingdeviated. When the spot adjustment lens 24 is displaced in the firstlens adjustment direction A1, by the projection piece 61, the dustproofmember 35 a can be prevented from being displaced toward the lightsensing device 30 and come off from the inner peripheral portion 53 ofthe partition wall 41.

In the embodiment, the dustproof member 35 a expands towards both theends 36 a in the axial direction, as compared with a dustproof member ofwhich both the ends in the axial direction are not deformed in the axialdirection, the dustproof member 35 a can be deformed in the axialdirection more easily. By providing the dustproof member 35 a with theprojection piece 61, even in the case where an external force in theaxial direction is applied to the dustproof member 35 a, the dustproofmember 35 a can be deformed in the axial direction more easily. With theconfiguration, the dustproof member 35 a can be prevented from exertingan adverse influence on the optical path 29 by, for example,interrupting the optical path 29 due to deformation of the innerperipheral face 37 of the dustproof member 35 a.

Third Embodiment

FIG. 6 is a cross section showing a part of the housing 40 of an opticalpickup device 10 b of a third embodiment of the invention. The opticalpickup device 10 b of the third embodiment is similar to the opticalpickup device 10 of the first embodiment, so that only different pointswill be described. In the optical pickup device 10 b of the thirdembodiment, components similar to those of the optical pickup device 10of the first embodiment are designated by the same reference numerals.In the optical pickup device 10 b of the third embodiment, in place ofthe dustproof member 35 of the optical pickup device 10 of the firstembodiment, a dustproof member 35 b which is formed in a bellows shapeis provided. In the example of FIG. 6, each of one end portion 55 b andthe other end portion 58 b of the dustproof member 35 b is formed in abellows shape. In a portion having a lens contact portion 56 b of theone end portion 55 b of the dustproof member 35 b, the inner peripheralface 37 and the outer peripheral face 60 expand toward the one endportion 55 b more greatly than the portion expands in the one endportion 55 b. The configuration prevents a situation such that, when thespot adjustment lens 24 is displaced in the first and second lensadjustment directions A1 and A2, the lens contact portion 56 b enters aninner space surrounded by the cylindrical body 24 a of the spotadjustment lens 24 and the state of contact with the spot adjustmentlens 24 is erroneously canceled. Therefore, the state of contact betweenthe lens contact portion 56 b and the spot adjustment lens 24 is heldwith reliability.

In the intermediate portion 38 b in the axial direction of the dustproofmember 35 b, two annular-shaped projection pieces 61 a and 61 b whichare disposed with a spacing in the axial direction and project to theoutside in the radial direction are provided around of the cylindricalportion of the right circular cylindrical shape. In a state where thedustproof member 35 b is provided for the partition wall 41, theprojection piece 61 a as one of the two projection pieces 61 a and 61 bis provided near to the one end portion 55 b of the dustproof member 35b and is in elastic contact with the surface 41 a facing the spotadjustment lens 24 of the partition wall 41. The other projection piece61 b is provided near to the other end portion 58 b of the dustproofmember 35 b and is in elastic contact with the other surface 41 b facingthe light sensing device 30 of the partition wall 41. The partition wall41 is sandwiched by the two projection pieces 61 a and 61 b from bothsides in the thickness direction. The two projection pieces 61 a and 61b prevent deviation in an axis line of the dustproof member 35 a withrespect to the housing 40 and deformation of the inner peripheral facein the intermediate portion 38 b in the axial direction due todisplacement of the spot adjustment lens 24 and the light sensing device30.

Further, the portion sandwiched by the spot adjustment lens 24 and thepartition wall 41 in the dustproof member 35 b is formed to be thinneras compared with that in the dustproof member 35 in the firstembodiment. When the spot adjustment lens 24 is displaced, in a statewhere only the one end portion 55 b of the dustproof member 35 b is mademore easily deformed in the axial direction, the dustproof member 35 bis held in the partition wall 41 by the two projection pieces 61 a and61 b without being positionally deviated. Even in the case where anexternal force in the axial directions is applied to the dustproofmember 35 b, the two projection pieces 61 a and 61 b can prevent thedustproof member 35 b from being come off from the inner peripheralportion 53 of the partition wall 41.

According to the embodiment, since the dustproof member 35 b is formedin a bellows shape, as compared with a dustproof member of which boththe ends in the axial direction are not deformed in the axial direction,the dustproof member 35 b can be deformed more easily in the axialdirection. Even in the case where an external force in the axialdirection is applied to the dustproof member 35 b, the dustproof member35 b is deformed in the axial direction, so that the dustproof member 35b can be prevented from exerting an adverse influence on the opticalpath.

Fourth Embodiment

FIG. 7 is a cross section showing a part of the housing 40 of an opticalpickup device 10 c in a fourth embodiment of the invention. FIG. 8 is anenlarged cross section of a section S in FIG. 7. The optical pickupdevice 10 c of the fourth embodiment is similar to the optical pickupdevice 10 a of the second embodiment shown in FIG. 5 and only differentpoints will be described. In the optical pickup device 10 c of thefourth embodiment, components similar to those of the optical pickupdevice 10 a of the second embodiment are designated by the samereference numerals. In the optical pickup device 10 c of the fourthembodiment, in the dustproof member 35 c, at least the surface of adevice contact portion 59 c which is in elastic contact with the lightsensing device 30 is formed as a curved surface. In the fourthembodiment, the surface of the lens contact portion 56 a of thedustproof member 35 c is not formed as a curved surface but the surfaceof the device contact portion 59 c of the dustproof member 35 c isformed as a curved surface. As compared with the case where the surfaceof the device contact portion is a plane, the contact area between thedustproof member 35 c and the light sensing device 30 is smaller, and africtional force generated by the displacement of the light sensingdevice 30 decreases. In the case where the light sensing device 30 isrotated around the reference axis line L15 and in the case where thelight sensing device 30 is displaced in the first and second adjustmentdirections B1 and B2, the influence exerted by displacement of the lightsensing device 30 can be reduced. Therefore, the other end portion 58 cof the dustproof member 35 c can be prevented from easily rotatingaround the reference axis line L15 and from being easily deformed in thefirst and second adjustment directions B1 and B2.

According to the fourth embodiment, the dustproof member 35 c is formedin such a manner that at least the surface of the device contact portion59 c which is in contact with the light sensing device 30 is formed as acurved surface. As compared with the case where the surface of thedevice contact portion 59 c is a plane, the contact area between thedustproof member 35 c and the light sensing device 30 can be madesmaller. Therefore, an influence exerted by displacement of the lightsensing device 30 can be reduced so as not to be easily exerted. Forexample, in the case of displacing the light sensing device 30 along avirtual plane perpendicular to the optical axis L24 of the spotadjustment lens 24, as compared with the case of displacing the lightsensing device 30 in the direction parallel to the optical axis L24, thedustproof member 35 c exerts an influence on the optical path due to adisplacement of the light sensing device 30 more easily. However, byforming the surface of the device contact portion 59 c of the dustproofmember 35 c as a curved surface, an influence exerted on the opticalpath due to displacement (the first and second adjustment directions B1and B2) of the light sensing device 30 can be reduced with reliability.The dustproof member 35 c can be also prevented from damaging the lightsensing device 30.

In the embodiment, only the surface of the device contact portion 59 cof the dustproof member 35 is formed as a curved surface. In addition,the surface of the contact portion 56 a which is in contact with thespot adjustment lens 24 may be also formed as a curved surface.

The foregoing first to fourth embodiments are just examples of theinvention and the configurations can be changed within the scope of theinvention. For example, the dustproof member may be disposed betweenother parts of an optical system, for example, in an optical pathextending between the light source 12 and the grating lens 20, in anoptical path extending between the beam splitter 21 and the spotadjustment lens 24, and the like. The surface of each of the lenscontact portion and the device contact portion of the dustproof memberin the first and third embodiments may be formed as a curved surface.The dustproof member may be formed in such a manner that only the innerperipheral surface is black and the other portion is a color other thanblack. The optical pickup device may have the function ofrecording/reproducing information to/from an optical recording mediumand, in addition, the function of erasing information from the opticalrecording medium.

Fifth Embodiment

FIG. 9 is a plan view of a main portion of an optical pickup device of afifth embodiment of the invention. FIG. 10 is a perspective view of amain portion of the housing in the fifth embodiment. FIG. 11 is a crosssection taken along line A-A of FIG. 9. FIG. 12 is a cross section takenalong line B-B of FIG. 9. FIG. 13 is a plan view of parts exploded fromthe optical pickup device in the fifth embodiment. In FIGS. 9 to 13, thesame components as those of the conventional optical pickup device inFIG. 18 are designated by the same reference numerals.

The optical pickup device has the housing 70 and various optical partsattached to the housing 70. The various optical parts include thehologram laser unit 71 capable of emitting and detecting a laser beam,and a dichromatic prism, a collimator lens, a reflection mirror, and anobjective lens which are not shown.

The optical pickup device of the invention is characterized by anattaching structure that an optical part including a light source foremitting a laser beam and/or a light sensing device capable of detectingthe laser beam like the hologram laser unit 71 is attached to thehousing 70.

The hologram laser unit 71 used in the embodiment will be describedbriefly. The laser unit 71 is a conventionally generally used one andhas a body portion 71 a of a rectangular block shape, the diffractiondevice 71 b attached to the tip of the body portion 71 a, and aplurality of terminals 71 d provided at the base end of the body portion71 a via a joint plate 71 c. The hologram laser unit 71 has dimensionssuch that overall length L (Z direction): 10.6 mm, width W (X direction)of the body portion 71 a: 6.6 mm, and thickness T (Y direction) of thebody portion 71 a: 3.0 mm.

The structure of attaching the hologram laser unit 71 to the housing 70will be described hereinbelow.

The housing 70 has, in a part of the periphery, a recess 90 forattaching an optical part, to which the hologram laser unit 71 isinserted in the horizontal direction and attached and, on both sides ofthe recess 90 in the peripheral end face, screw holes 80, 80 forattaching the hologram laser unit 71 to the recess 90.

The recess 90 for attaching an optical part is a recessed groove whichopens in the horizontal direction (Z direction) and upward. The openingin the horizontal direction is an insertion port 91 to which thehologram laser unit 71 is inserted. In the deep portion of the recess90, a groove-shaped optical path 92 is formed in the optical path lengthdirection (Z direction). The optical path 92 is communicated with arecessed portion 93 for housing a not-shown dichroic prism, a collimatorlens, or the like. Further, the recess 90 has a step on each of theright and left inner side faces, which is narrowed in a position to thedepth side a little from the insertion port 91. On the side deeper thanthe step, a temporary holding portion 72 is provided, which regulatesmovement of the hologram laser unit 71 in the vertical direction Ydirection) perpendicular to the bottom face 90 a of the recess 90 so asto be able to temporary hold the hologram laser unit 71 for positionadjustment of the hologram laser unit 71 at least in the optical pathlength direction.

The temporary holding portion 72 is constructed by a pair of upper andlower projection pieces 72 a and 72 b which project to the inside from aleft inner face 90 b and a pair of upper and lower projection pieces 72c and 72 d which project to the inside from a right inner face 90 ctoward the insertion port 91 of the recess 90 which is open in thehorizontal direction in an almost intermediate position in the opticalpath length direction (Z direction) of the recess 90. The under face ofeach of the projection pieces 72 a and 72 c on the upper side and thetop face of each of the projection pieces 72 b and 72 d on the lowerside are formed as opposed faces parallel to each other in thehorizontal direction. In this case, the top face of each of the upperprojection pieces 72 a and 72 c is flush with the top face of thehousing 70. The projection pieces 72 b and 72 d on the lower side areformed on the bottom face 90 a of the recess 90.

The interval A₁ between the projection pieces 72 a and 72 c on the upperside and the projection pieces 72 b and 72 d on the lower side is setalmost equal to the thickness T of the hologram laser unit 71. Theinterval A₂ between the projection pieces 72 a and 72 b on the left sideand the projection pieces 72 c and 72 d on the right side is set to besmaller than the width W of the hologram laser unit 71. In the case ofthe embodiment, the interval A₁ is set to be about 3.0 mm and theinterval A₂ is set to be smaller than 6.6 mm. The interval A₃ betweenthe left inner face 90 b and the right inner face 90 c is set to belarger than 6.6 mm. Each of the projection pieces 72 a, 72 b, 72 c, and72 d is formed in a square bar having a length (X direction) of 2.3 mm,a width (Z direction) of 1.8 mm, and a thickness (Y direction) of 0.8mm. The interval A₁ and the thickness of the projection pieces 72 b and72 d on the lower side are set so that the laser unit 71 is temporarilyheld to make the optical axis of the laser unit 71 parallel to thedesigned optical axis and coincide with the height of the designedoptical axis by inserting the laser unit 71 in a space consisting of theprojection pieces 72 a, 72 b, 72 c, and 72 d. The projection pieces 72a, 72 b, 72 c, and 72 d also serve as portions to which an adhesive isapplied for fixing the position of the laser unit 71. This will bedescribed later.

Between the left and right inner faces 90 b and 90 c and the deep wallface in the recess 90, bent wall faces 90 d and 90 e by which the widthis narrowed toward the deep side are provided. In positions in contactwith the bent wall faces 90 d and 90 e in the bottom face 90 a, a pairof attachment steps (protrusion) 76 a and 76 b having an isoscelestriangle shape for attaching the elastic buffer 74 which will bedescribed later are provided. In the case of the embodiment, each of theattachment steps 76 a and 76 b is set to have a hypotenuse of 2.1 mm,the other side of 1.5 mm, and a thickness of 0.8 mm. The attachmentsteps 76 a and 76 b are used as portions to which an adhesive is appliedfor adhering the elastic buffer 74 to the recess 90 and are set to havethe thickness so as to hold the elastic buffer 74 in a predeterminedheight position.

The optical pickup device of the invention has the elastic buffer 74attached to the deep portion of the recess 90. The elastic buffer 74takes the form of a black sponge made of plastic having an arbitraryelasticity and is formed in an outer shape almost the same as the spacedeeper than the projection 72 in the recess 90. The elastic buffer 74has therein a housing recess 74 a having a size in which the wholediffraction device 71 b of the hologram laser unit 71 can be insertedwith a margin and has, on the opening side (projection 72 side) of thehousing recess 74 a, a fitting recess 74 b in which the front end sideof the body 71 a is fit. In the front end face of the elastic buffer 74,a laser beam passing window (not shown) communicated with the housingrecess 74 a is formed. At the time of attaching the elastic buffer 74 tothe deep portion of the recess 90, an adhesive 73 a is preliminarilyapplied to the top face of the pair of attachment steps 76 a and 76 b,the elastic buffer 74 is inserted from the upper opening of the recess90, and two portions in the under face are fixed by the adhesive 73 a.

An example of the procedure (assembling method) of attaching thehologram laser unit 71 to an attachment structure provided for thehousing 70 will now be described.

In the housing 70, the elastic buffer 74 is preliminarily attached tothe recess 90 as described above.

Process (1)

The laser unit 71 is inserted from the diffraction device 71 b side intothe insertion port 91 of the housing 70 and the diffraction device 71 bis inserted in the housing recess 74 a in the elastic buffer 74. At thistime, even if the laser unit 71 is excessively pushed into the recess90, the elastic buffer 74 plays the role of a cushion to prevent thediffraction device 71 b from coming into direct contact with the innerface of the recess 90 and from being destroyed. When the diffractiondevice 71 b is housed in the housing recess 74 a in the elastic buffer74, a dustproof effect and a light shielding effect are obtained and,accordingly, a higher pickup precision is obtained. On the other hand,the tip portion of the body 71 a is fit in the fitting recess 74 b inthe elastic buffer 74 and the intermediate portion is inserted betweenthe projection pieces 72 a and 72 c on the upper side and the projectionpieces 72 b and 72 d on the lower side. The laser unit 71 is temporarilyheld (sandwiched) in a state where movement in the vertical direction (Ydirection) is regulated.

Process (2)

The position of the laser unit 71 temporarily held by the projections 72is adjusted in the optical path length direction (Z direction) and thehorizontal direction (X direction) by using, for example, a positionadjusting tool. Since the elastic buffer 74 is a sponge having moderateelasticity, while pushing the diffraction device 71 b as a device at thetip of the laser unit 71 against the elastic buffer 74, the diffractiondevice 71 b can be slightly moved easily in the optical path lengthdirection without coming into contact with the wall face in the deepportion of the recess 90. The position adjustment in the verticaldirection (Y direction) of the laser unit 71 is performed by temporaryholding the laser unit 71 by the projections 72.

Process (3)

An adhesive (preferably, an instantaneous adhesive of which hardeningtime is extremely short) is applied to a contact portion between theprojection pieces 72 a and 72 c on the upper side and the top face ofthe body 71 a of the laser unit 71 and a contact portion between theprojection pieces 72 b and 72 d on the lower side and the under face ofthe body 71 a of the laser unit 71, concretely, a portion in which avertical face of each of the projection pieces and the contact face ofthe laser unit 71 are in contact with each other, thereby fixing thelaser unit 71 to the projections 72.

Process (4)

The terminals 71 d of the laser unit 71 are inserted in a plurality ofterminal insertion holes of the laser pressing spring 75, the screws 79are inserted in the holes 78 formed in both the ends of the laserpressing spring 74, and the screws 79 are screwed in the screw holes 80formed in the housing 70. By inserting the terminals 71 d in a pluralityof holes in the FPC 81 and soldering the conductive lands around theholes and the terminals 71 a, the laser unit 71 is securely fixed in astate where the position of the laser unit 71 is adjusted at highprecision with respect to the housing 70.

As described above, the invention has advantages that the spaceadjustment in the optical path direction of the laser unit 71 is enabledand, in addition, the laser holder (refer to FIG. 18) which is requiredconventionally and is not easily processed is unnecessary. The precisionof a laser beam emitted to the collimator lens is improved andmore-reliable recording to a high-density optical disk medium can beachieved. Damage of the laser unit 71 can be prevented and reduction infraction defective and cost at the time of manufacturing an opticalpickup device can be realized.

Other Embodiment

1. In the foregoing fifth embodiment, as shown in FIG. 10, the case thatthe recess 90 of the housing 70 has a recessed groove shape having thebottom face 90 a was described. However, other structures may be alsoused such that an optical part is inserted in the recess and temporarilyheld (sandwiched) by projection pieces, positional adjustment isperformed, and after that, a window for applying an adhesive is formedaround the projection piece on the lower side on the bottom face so thatthe adhesive can be easily applied to the contact portion between theprojection piece on the lower side and the optical part. Alternately,the bottom face may not be provided.2. In the foregoing fifth embodiment, the case of attaching the hologramlaser unit 71 for emitting a laser beam and receiving and detecting thelaser beam to the recess 90 in the housing 70 has been described.However, a semiconductor laser for only emitting a laser beam or a lightsensing device for only receiving and detecting a laser beam may beattached to the recess 90.

According to the invention, the full periphery of the optical pathextending between the opposed lens and the light sensing device iscovered with the cylindrical dustproof member. With the configuration,intrusion of the foreign matter such as dusts can be prevented. It cansolve the problem such that light from the spot adjustment lens isscattered by the foreign matter and led to the undesired light receptionposition of the light sensing device. Therefore, the performance of theoptical pickup device can be held preferably.

Further, according to the invention, the dustproof member is made of anelastic material. Consequently, even if an external force is applied tothe dustproof member, the external force can be absorbed and theposition in which the dustproof member is disposed can be prevented frombeing undesirably deviated. Thus, the state in which the optical pathextending between the opposed lens and the light receiving device iscovered can be maintained. Further, in the case of providing thedustproof member for the housing or the like, by providing the throughhole and a retaining member such as the pair of projection pieces forthe housing, without using another holding member such as the adhesive,the dustproof member can be easily provided for the retaining member andheld by the housing. Consequently, the workability can be improved andthe number of parts of the device can be prevented from increasing.

Further, according to the invention, the one end portion in the axialdirection of the dustproof member is elastically in contact with thefull periphery of the opposed lens, and the other end portion in theaxial direction of the dustproof member is elastically in contact withthe full periphery of the light sensing device. Consequently, even inthe case where the position is adjusted by displacing the opposed lensand the light sensing device, the dustproof member can be maintained inthe contacting state between the opposed lens and the light sensingdevice. Therefore, intrusion of a foreign matter to the optical pathextending between the opposed lens and the light sensing device can beprevented with reliability.

Further, according to the invention, since the dustproof member expandstowards both the ends in the axial direction, the dustproof member canbe deformed in the axial direction more easily as compared with adustproof member whose both the ends are not deformed in the axialdirection. Even in the case where an external force in the axialdirection is applied to the dustproof member, the dustproof member iseasily deformed in the axial direction, so that the dustproof member canbe prevented from exerting an adverse influence on the optical path.

Further, according to the invention, the dustproof member is formed in abellows shape. Consequently, as compared with a dustproof member whoseboth the ends in the axial direction are not deformed in the axialdirection, the dustproof member can be deformed in the axial directionmore easily. Thus, even in the case where an external force in the axialdirection is applied to the dustproof member, the dustproof member iseasily deformed in the axial direction, so that the dustproof member canbe prevented from exerting an adverse influence on the optical path.

According to the invention, the light sensing device is held by thehousing so as to be rotatable around the reference axis line which isparallel to the optical axis of the opposed lens and displaceable in thedirection perpendicular to the reference axis line. The opposed lens isheld by the housing so as to be displaceable along the optical axis. Thedustproof member is held by the housing so that both the ends in theaxial direction are displaceable in the intermediate portion in theaxial direction. With the configuration, even in the case where thelight sensing device and the spot adjustment lens are displaced withrespect to the housing, the dustproof member is not easily influenced bythe displacement. In other words, even in the case where the lightsensing device and the opposed lens are displaced with respect to thehousing as described above, the axial layout state of the dustproofmember can be maintained. It can prevent a change in the axial layoutstate of the dustproof member and exertion of an adverse influence onthe optical path. Therefore, the dustproof effect can be held withreliability.

According to the invention, the dustproof member is formed in such amanner that at least the surface of a contact portion which is incontact with the light sensing device is formed as a curved surface. Ascompared with the case where the surface of the contact portion which isin contact with the light sensing device is a plane, the contact areabetween the dustproof member and the light sensing device can be madesmaller. Therefore, an influence exerted by displacement of the lightsensing device can be reduced so as not to be easily exerted. Forexample, in the case of displacing the light sensing device along avirtual plane perpendicular to the optical axis of the spot adjustmentlens, as compared with the case of displacing the light sensing devicealong the optical axis, the dustproof member exerts an influence on theoptical path due to a displacement of the light sensing device moreeasily. However, by forming the surface of the contact portion which isin contact with the light sensing device of the dustproof member as acurved surface, an influence exerted on the optical path due todisplacement of the light sensing device can be reduced withreliability. The dustproof member can be also prevented from damagingthe light sensing device.

According to the invention, at least the inner peripheral face of thedustproof member is black, so that light can be prevented from beingirregularly reflected by the inner peripheral face of the dustproofmember. Consequently, stray light generated by irregular reflection canbe reliably prevented from being received by the light sensing device.

According to the invention, at the time of attaching the optical partsuch as the hologram laser unit, the semiconductor laser, the lightsensing device, or the like to the housing, by providing the elasticbuffer in the attachment position, the light source and/or the lightsensing device are/is protected by the elastic buffer. The light sourceand/or the light sensing device can be prevented from coming intocontact with the wall of the housing made of a metal or plastic having acertain degree of strength and from being damaged. As described above,since the optical part is protected by the elastic buffer, the breakageratio largely decreases, the laser holder which is conventionallynecessary becomes unnecessary, a manufacturing process and the number ofparts of a laser holder which is not easily processed can be reduced,and attachment of the laser holder to the house and the positionaladjustment which are conventionally performed are not performed. Thus,the manufacturing cost is largely reduced and the assembly workabilityimproves.

The adjustment space in the optical path length direction is assured bythe elastic buffer, so that the optical part can be (slightly) moved inthe optical path length direction by elastic deformation of the elasticbuffer at the time of adjusting the position of the optical part in theoptical path length direction, and the positional adjustment can beperformed easily at high precision. Therefore, the precision of thelaser beam (diffusion light) emitted to the collimator lens and/orprecision of a laser beam (focused beam) from the collimator lens isimproved, and information can be recorded/reproduced to/from ahigh-density optical device medium more reliably.

1. An optical pickup device, comprising: a housing; an optical partwhich is attached to the housing and includes a light source foremitting a laser beam and/or a light sensing device capable of detectingthe laser beam; and an attaching structure which is provided in anoptical part attaching position in the housing and can attach theoptical part directly to the housing, wherein the attaching structurehas an elastic buffer for protecting the light source and/or the lightsensing device of the optical part at the time of attaching the opticalpart to the housing and adjusting the position of the optical part in anoptical path length directions, wherein the recessed portion of theattaching structure has a temporary holding portion so that the opticalpart is temporarily held in a state where movement in the verticaldirection is regulated.
 2. The device of claim 1, wherein the housinghas a recessed portion for inserting and attaching the optical part inthe horizontal optical path direction and has a structure that theelastic buffer is disposed along the wall face in the deep portion ofthe recess.
 3. The device of claim 1, wherein the temporary holdingportion has a structure formed on an inner face of the recessed portionand sandwiching the optical part inserted in the recessed portion fromtop and bottom.
 4. The device of claim 3, wherein the temporary holdingportion can also serve as a portion to which an adhesive for fixing theoptical part sandwiched from top and bottom is applied.
 5. The device ofclaim 1, wherein the recessed portion of the attaching structure has aprotrusion to which an adhesive is applied for fixing the elasticbuffer.
 6. The device of claim 1, wherein the optical part is a hologramlaser unit.